1. Field of the Invention
The present invention relates to a thin-film magnetic head with a plurality of magnetoresistive effect (MR) read head elements, and to a magnetic medium drive apparatus with this thin-film magnetic head.
2. Description of the Related Art
U.S. Pat. No. 6,246,553 discloses a magnetic head with an MR head element, in which electrical potential in the head and related charge accumulation are clamped by electrically connecting a shield layer and a lead line in the MR element each other through a resistor so as to prevent noise spike from occurring.
Japanese patent publication No. 2002-100009A discloses a magnetic head with an MR element, in which a ground for an MR film and a ground for a shield layer in the MR element are connected to the common ground so as to prevent electrostatic discharge (ESD) between the shield layers and the MR film.
According to such known techniques disclosed in U.S. Pat. No. 6,246,553 and Japanese patent publication No. 2002-100009A, the shield layers and the MR film are electrically connected each other. However, in some magnetic medium drive apparatuses, their specifications may require to absolutely provide electrical isolation between the shield layers and the MR film and, therefore, such known technique cannot be utilized at all. Also, in a giant magnetoresistive effect (GMR) read head element and a tunnel magnetoresistive effect (TMR) read head element with a current perpendicular plane (CPP) structure in which a sense current flows in a direction perpendicular to laminated layer surfaces or film surfaces, because the shield layers and the MR film are electrically connected inherently, no effect can be derived even if the shield layers and the MR film are electrically connected each other as done in the known technique.
Further, although the shield layers and the MR film are grounded according to the known technique disclosed in Japanese patent publication No. 2002-100009A, such known technique cannot be adopted to certain magnetic medium drive apparatuses in which both the shield layers and the MR film have to be not grounded for preventing entering of noises from the ground.